A virtual private network is a private communication network used to communicate confidentially over a publicly accessible network. VPN message traffic can be carried over a public network infrastructure, such as the Internet, on top of standard protocols. VPNs are used, for example, to enable employees to connect securely to a corporate network.
VPN connections are used to carry both data traffic and control traffic. The control traffic is used to maintain a VPN connection or to ensure that the connection is still active. For example, a VPN tunnel may proceed through a firewall/network address translation (NAT), which may close the tunnel if no traffic is detected for a certain time period. Thus, in many cases, a VPN client or server may send messages to the firewall/NAT to keep the tunnel open. In other cases, control messaging can be provided between a VPN client and a VPN server in order to ensure that the connection is still active.
However, if the VPN connection is not being used for data transfer, the control messaging between the VPN client and VPN server still utilize network resources and further, if the VPN client is on a device has an internal power source, then such traffic uses power source resources.